The four volume set LNAI 3681, LNAI 3682, LNAI 3683, and LNAI 3684 constitute the refereed proceedings of the 9th International Conference on Knowledge-Based Intelligent Information and Engineering Systems, KES 2005, held in Melbourne, Australia in September 2005. The 716 revised papers presented were carefully reviewed and selected from nearly 1400 submissions. The papers present a wealth of original research results from the field of intelligent information processing in the broadest sense. The second volume contains papers on machine learning, immunity-based systems, medical diagnosis, intelligent hybrid systems and control, emotional intelligence and smart systems, context-aware evolvable systems, intelligent fuzzy systems and control, knowledge representation and its practical application in today's society, approaches and methods into security engineering, communicative intelligence, intelligent watermarking algorithms and applications, intelligent techniques and control, e-learning and ICT, logic based intelligent information systems, intelligent agents and their applications, innovations in intelligent agents, ontologies and the semantic web, knowledge discovery in data streams, computational intelligence tools techniques and algorithms, watermarking applications, multimedia retrieval, soft computing approach to industrial engineering, and experience management and information systems.